Infrastructure protectionRising sea levels make NYC vulnerable to more frequent, more intense floods

Scientists say that Hurricane Sandy has forced a recognition on New York City and on other coastal communities: the steady rise in sea levels means not only more floods, but more frequent and more devastating floods; three of the top 10 highest floods at the Battery since 1900 happened in the last two and a half years; after rising roughly an inch per decade in the last century, coastal waters in New York are expected to climb as fast as six inches per decade, or two feet by midcentury; the city is exploring a $10 billion system of surge barriers and huge sea gates

Scientists say that Hurricane Sandy has forced a recognition on New York City and on other coastal communities: the steady rise in sea levels means not only more floods, but more frequent and more devastating floods.

Sea levels have been rising as a result of the increasing emissions of CO2 into the atmosphere, a by-product of the industrial revolution and the rise in the standard of living. Both developments have led to the burning of more CO2-rich fossil fuel.

The New York Timesreports that a study by city-appointed scientific panel reported that after rising roughly an inch per decade in the last century, coastal waters in New York are expected to climb as fast as six inches per decade, or two feet by midcentury.

The administration of Governor Andrew Cuomo is considering building a system of storm barriers and huge sea gates at the cost of about $10 billion, but coming up with the money in these tight fiscal times will not be easy.

Scientists and engineers say that doing nothing in the face of rising sea level would be much more expensive. “Look, the city is extremely vulnerable to damaging storm surges just for its geography, and climate change is increasing that risk,” Ben Strauss, director of the sea level rise program at the Princeton, New Jersey-based Climate Central, told the Times. “Three of the top 10 highest floods at the Battery since 1900 happened in the last two and a half years. If that’s not a wake-up call to take this seriously, I don’t know what is.”

The havoc wreaked by Sandy was accurately predicted by various scientific panels studying the growing vulnerability of New York to sea level rise: subway tunnels flooded with water, loss of power for millions, destructions of buildings; and economic damage.

Observers of city politics are not convinced t that once the clean-up is completed, city leaders will begin to work on the long-term project necessary to make the city more resilient in the face on an increasingly unforgiving nature. One former official, who spoke with the Times on the condition of remaining anonymous, said it had been difficult to move from theoretical planning to concrete actions.

“A fair question to ask is, have we been as focused as we need to be for emergency preparations,” he said. “We’ve just been lucky. We need hardening for the risk we’ve always faced. Until things happen, people aren’t willing to pay for it.”

The city growing vulnerability has also led the State of New York to appoint a panel of scientists and engineers to examine possible solutions. The state report on the risk rising sea levels pose for the city was issued on the last day of Governor David Paterson’s administration in 2010. The report suggested building structural barriers to restrain floodwaters, and that these barriers should be one element of a broader solution, which would also involve relocating buildings and people farther from the coasts.

The idea of installing surge barriers to protect cities from floods is not new, and several cities in the United States and Europe have installed them. The gates are kept open during normal times, but when a major storm is anticipated, the gates are closed to prevent the surging water from inundating the protected areas.

Eight years ago, in 2004, the Storm Surge Research Group at Stony Brook University developed a proposal which argued for building three movable barriers. The barriers would be installed at the upper end of the East River near the Throgs Neck Bridge, under the Verrazano-Narrows Bridge, and at the mouth of the Arthur Kill between Staten Island and New Jersey. The proposal said the system would protect large sections of the city (see “Flood-proofing New York City with storm barriers,” HSNW, 1 June 2009).

The Times notes that some experts consider the barriers a last resort, and urge more modest changes, including subway floodgates. Both the city and the state have been exploring plans to make the Metropolitan Transportation Authority and Consolidated Edison systems more robust in the face of storms, and some of the work recommended by expert task forces is already being done.

In the wake of the flood which shut down the subways for several hours in 2007, the transit agency spent $34 million on some flood protections, but no additional funds were allocated for the project.

Robert Puentes of the Brookings Institution told the Times that the city, to its credit, had developed a coastal storm plan that treated seriously the city’s susceptibility, given its 520-mile coastline, but that “most of that focuses on mapping a response to the disaster after it already occurs.”